Disk drive unit is a kind of information storage device used widely in the world. The disk drive unit has a very small slider incorporating a read/write transducer therein. The slider is flying above a rotary magnetic medium such as a disk, and moves selectively from track to track of the disk surface to read data from or write data to the disk.
FIG. 1 shows an ideal slider. The slider 100 comprises a planar air bearing surface (ABS) 102. An alumina layer 104 formed at a front side of the slider 100, and a pole 101 is formed at a top portion of the alumina layer 104 to perform data reading/writing operation. A plurality of connecting pads 106 are formed on the alumina layer 104 for electrically connecting the slider 100 with a suspension disposed in the disk drive unit.
However, for making the slider taking off more easily, ABS 204 of an actual slider 200 is a camber-curved surface for aerodynamics concern, as shown in FIG. 2. The camber-curved surface is formed as follows: deforming the slider along its length direction to generate a camber deformation (the deformation is referred as total crown) 202 at the ABS side; deforming the slider along its width direction to generate a camber deformation at the ABS side (the deformation is referred as total cross crown) 206; and deforming the slider along its diagonal direction to generate a camber deformation at the ABS side (the deformation is referred as twist) 203.
The total cross crown (TCC) has two kinds of deformation forms: (1) negative deformation, that is, along the width direction of the ABS side of the slider, a middle portion thereof is lower than both end portions thereof, e.g. as shown in FIG. 3a, the TCC at the side of ABS 304 of the slider 300 is a negative deformation; and (2) positive deformation, that is, along the width direction of the ABS side of the slider, a middle portion thereof is higher than both end portions thereof, e.g. as shown in FIG. 3b, the TCC at the side of ABS 404 of the slider 400 is a positive deformation. In addition, it is usually thought that a slider with positive deformation (TCC) makes disk drive unit have a better and more stable performance, therefore, sliders with positive deformation (TCC) are used in disk drive units for improving working performance thereof. Up to now, there are various manufacturing methods for forming sliders with positive deformation (TCC).
As is known to all, an individual slider is formed by the following steps: processing a row bar constructed by a plurality of slider bodies, and then cutting the row bar into sliders along a plurality of predetermined marks thereon. More specifically, the camber-curved surface is formed by grinding the surface for forming the ABS of the row bar with a specific grinding device; while the cutting process is preformed by a cutter, such as a diamond cutting wheel.
As shown in FIGS. 4a-4b, a manufacturing method for forming sliders with positive deformation (TCC), referred as “row grooving method”, includes the following steps: firstly, providing a row bar 500 having an alumina layer 502 at one end thereof, wherein a plurality of poles 501 spaced with each other are formed on the alumina layer 502 along a length direction of the row bar 500; Then, forming a plurality of grooves 504 with a certain width on both ABS 506 and the alumina layer 502 of the row bar 500 along a plurality of cutting lines 503; After that, the surface 506 having grooves 504 therein are pressed against a concave grinding surface 602 of a grinding plate 600 and ground, thereby a positive deformation (TCC) on the surface 506 are formed; Then, the row bar 500 are cut along the cutting lines 503 (at both sides of each groove 504) by a cutter, such as a diamond cutting wheel, to produce a plurality of individual sliders 400 (see FIG. 3b). However, during the cutting process, it is prone to produce side surface stress (cutting stress) on fracture face of the slider 400, and the side surface stress is difficult to eliminate or weaken during the cutting process or after the cutting process. As a result, edge jumps 407 are formed at both ends of the ABS 404 along a width direction of the slider 400. When the slider 400 flies above the disk, the ABS 404 thereof faces to the disk surface, and only a very small flying height is maintained between the ABS 404 and the disk surface. Since these edge jumps 407 are formed at both ends of the ABS 404 along the width direction of the slider 400, when an impact or shock happens to the disk drive, these edge jumps 407 on the slider 400 has a danger to scratch the disk surface so as to damage the disk and/or slider, and thus debasing working performance of the disk drive. Furthermore, as a plurality of grooves are formed on the alumina layer 502, so a continuity of the transducers (poles) in the alumina layer 502 is broken. However, for some type of wafers, such as tunnel magneto-resistive (TMR) wafers, transducers in the alumina layer 502 must be continuous. As a result, the manufacturing method cannot manufacture e.g. tunnel magneto-resistive (TMR) wafers, i.e., the method has a great limitation in use.
FIGS. 5a-5b illustrate another slider manufacturing method referred as “single scribing line method”. The method includes the following steps: firstly, scribing a point scribe line 709 at a middle position between two cutting lines 703 on an ABS 706 of a row bar 700 using a scribing tool, such as a laser scriber; Then, pressing the ABS 706 against a concave grinding surface 602 of a grinding plate 600 for grinding so as to generate a positive deformation (TCC) on the ABS 706; After that, cutting the row bar 700 along the cutting lines 703 by a cutter, such as a diamond cutting wheel to produce a plurality of individual sliders 400 (see FIG. 3b). Because the point scribe lines 709 are scribed by the scriber only on the ABS 706, but not on the alumina layer 702, so the alumina layer 702 can be protected effectively. However, side surface stress is still produced on fracture face of the slider 400, and difficult to eliminate or weaken during the cutting process or after the cutting process. Consequently, a plurality of clear edge jumps 407 still remains at edges of the slider 400, which maybe cause damage to the slider and /or the disk.
In addition, as shown in FIG. 3a, when producing a negative deformation (TCC) using the abovementioned method, a plurality of clear edge jumps 305 are still generated at both ends of the ABS 304 along a width direction of the slider 300.
For eliminating or reducing the side surface stresses generated in row bar cutting region (side portion of slider) during cutting process, so as to avoid producing edge jumps or reduce height of edge jumps on the slider, there is a need to provide an improved slider manufacturing method to solve the above-mentioned problems.